Crate cvar

Configuration Variables allow humans to interactively change the state of the program.

Let's use an example to see how we can make it interactive. The following snippet defines our program state with a user name and a method to greet the user:

pub struct User {
    name: String,
}
impl User {
    pub fn greet(&self, console: &mut cvar::IConsole) {
        let _ = writeln!(console, "Hello, {}!", self.name);
    }
}

Implement the IVisit trait to make this structure available for interactivity:

impl cvar::IVisit for User {
    fn visit_mut(&mut self, f: &mut FnMut(&mut cvar::INode)) {
        f(&mut cvar::Property("name", "description", &mut self.name, String::new()));
        f(&mut cvar::Action("greet!", "description", |_args, console| self.greet(console)));
    }
}

That's it! Create an instance of the structure to interact with:

let mut user = User {
    name: String::new(),
};

Given unique access, interact with the instance with a stringly typed API:

// Give the user a name
cvar::console::set(&mut user, "name", "World").unwrap();
assert_eq!(user.name, "World");

// Greet the user, the message is printed to the console string
let mut console = String::new();
cvar::console::invoke(&mut user, "greet!", &[""], &mut console);
assert_eq!(console, "Hello, World!\n");

This example is extremely basic, for more complex scenarios see the examples.

Modules

console

Interact with the configuration variables.

Structs

Action	Action node.
ClampedProp	Property node with its value clamped.
IoConsole	Io console for actions.
List	List node.
NullConsole	Null console for actions.
OwnedProp	Property node which owns its variable.
Property	Property node.
ReadOnlyProp	Read-only property node.
VisitMut	Node visitor from closure.

Enums

NodeMut	Enumerates derived interfaces for downcasting.
PropState	Property state.

Traits

IAction	Action node interface.
IConsole	Console interface for actions to write output to.
IList	List of child nodes.
INode	Node interface.
IProperty	Property node interface.
IVisit	Node visitor.

Functions

Action
ClampedProp
List
OwnedProp
Property
ReadOnlyProp